Electro-magnetic pump



FIF8502 June 28, 1966 G. N. J. MEAD ELECTRO-MAGNETIC PUMP 4 Sheets-Sheet 1 Filed Nov. 4, 1963 F I G. 5

INVENTOR.

GEORGE N. a. MEAD ATTORNEYS June 28, 1966 G MEAD 3,257,949

ELECTRO-MAGNETIC PUMP Filed Nov. 4. 1963 4 Sheets-Sheet 2 OUTER- MAGNETIG IRON JACKET], [oooooooooooooool [oooooooooooooool SPIRALS FOR My GUIDING /6 PUMPING AN mus TRIc CURRENT IOQOOOOOOOOOOOOOI 6 IQOOOOOOOOOOOOOO] 64 RA MAGNETIC IRQN CORE Q {0000000000000001 [0000000000000001 6 2 2 F IG. 7 N 38 N Ioooooooooobooool I foooooooooooooooI /4J /6 [OUTER ANNULUS N N I Mim 2 s s I \INNER ANNULUS 3 s s I E FLUID FLOW I I I CENTRAL MAGN E T!C IRON CORE FIG. 9

INVENTOR.

GEORGE N. J MEAD W I m- ATTORNEYS June 28, 1966 G. N. J. MEAD 3,257,949

ELECTRO-MAGNETI C PUMP Filed Nov. 4, 1963 4 Sheets-Sheet 3 INVENTOR.

GEORGE N. J. MEAD ATTORNEYS June 28, 1966 G. N. J. MEAD ELECTRO-MAGNETIC PUMP 4 Sheets-Sheet 4 Filed Nov. 4, 1963 FIG.

INVENTOR.

GEORGE N. J. MEAD ATTORNEYS United States Patent 3,257,949 ELECTRO-MAGNETIC PUMP George N. J. Mead, Robin Lane, Exeter, N.H. Filed Nov. 4, 1963, Ser. No. 321,071 16 Claims. (Cl. 103-1) The present invention is directed towards electromagnetic pumps and more particularly is directed towards improvements in electro-magnetic pumps of the sort disclosed in my copending application, Serial No. 306,519, now Patent No. 3,198,119.

In my copending application, there is described an electro-magnetic pump in which an electrically conductive fluid is moved axially along a conduit by the interaction of sets of concentric overlapping magnetic fields, some of which are fixed with respect to the conduit and some of which are formed by electrical currents passing spirally through the fluid from the conduit walls towards the conduit axis.

In general, magnetic pumps operate on the principle that a force is exerted upon a conductor (the fluid) carrying a current in a magnetic field. The high electrical conductivity of liquid metals makes it possible to pump by electromagnetic means. For use in nuclear reactors where a minimum amount of maintenance is desirable, electromagnetic pumps are preferable to conventional mechanical pumps, because they have no moving parts, bearings or seals. It has been found, for example, that highly corrosive liquid sodium, which is used as the primary coolant and moderator in some pressurized reactors, is particularly diflicult to handle because of the rapid deterioration of the various pump components.

To avoid this problem electro-magnetic pumps are often employed since they have no moving parts and they can be fabricated from materials that are substantially inert to corrosive liquids. In addition to reactor systems, electro-magnetic pumps are also employed in transferring liquid or powdered metals, moving columns of mercury to operate actuators, mixing of molten metals in furnaces, pumping of liquid metals to die casting equipment, and various other applications.

Heretofore, direct current conduction pumps embodied applications of Flemings right-hand rule. Pumps of this type operate at very high current and low voltage levels and have been characterized by poor operating efficiency as a result of high pumping losses and by armature reaction or eddy current losses.

In my copending application, there is disclosed an electro-magnetic pump adapted to operate at a much higher voltage and lower current level than Fleming-type electro-magnetic pumps. The pump disclosed in the application is substantially more efficient than other pumps of this type and is capable of high pressure operation with a relatively simple mechanical configuration.

The pump shown in my copending application features the use of spiral baflles extending between the walls of the conduit and the center axis thereof in order to provide spiral fluid paths for electrical currents to travel whereby magnetic fields may be developed. A series of fixed coils, concentric with and overlapping the fluid coils are employed to coact with the fields formed by the fluid coils in such a fashion so as to pump the fluid axially along the conduit. In the pump disclosed in my copending application, there are problems of current leakage whereby a relatively large portion of the electric current follows a shorter path than that formed by the spiral battles and thereby fails to produce the optimum magnetic field for interaction with the fixed magnetic fields.

Accordingly, it is an object of the present invention to provide improvements in electro-magnetic pumps.

Another object of this invention is to prevent current leakage in electro-magnetic pumps of the sort employing the interaction of fixed and fluid electro-magnetic coils.

Still another object of this invention is to maximize the pressure exerted on the conductive fluid in an electromagnetic pump.

More particularly this invention features an electromagnetic pump comprising a conduit having fixed coils wound about its outer surface with adjacent coils arranged in opposing polar relationship. Mounted within the conduit are at least two interleaved, electrically insulated spiral baflies with the outer ends of the baflies attached to the inner wall of the conduit at spaced points of connection to define two separate spiral passages between the conduit wall and a conductive rod extending axially along the conduit. Two strip electrodes of opposite polarity are mounted on the conduit wall, one at the outer end of each spiral passage. Sections of each electrode are alternately exposed and insulated whereby an applied electric current will spiral inwardly to the central conductor in one section of the conduit, advance axially along the conductor and then spiral outwardly in an adjacent section of the conduit, thus producing fluid electro-magnets having magnetic fields that are opposed to each other. Only one of the two spiral passages in each section are used at one time. The fields set up by the fluid solenoids co-act with fields formed by fixed windings on the conduit causing the fluid within the conduit to be pumped axially along the conduit.

As another feature of this invention, the axial core of the pump is magnetic and is provided with windings arranged in the same direction as those which make up the fixed coils. When the coil windings are energized in conjunction with the energization of the fixed conduit coils, the magnetic flux from the fixed conduit windings is forced to the center line of the conduit before passing axially towards the opposite pole. This has the effect of creating a stronger fixed magnetic pole by reducing the flux leakage and it makes possible higher pressure output for the pump.

But these and other features of the invention, along with further objects and advantages thereof, will become more fully apparent from the following detailed description of preferred embodiments of the invention, with reference being made to the accompanying drawings in which:

FIG. 1 is a view in perspective, somewhat schematic of an electro-magnetic pump made according to the invention,

FIG. 2 is an exploded view in perspective, graphically illustrating the fluid coil arrangements formed by the pump of FIG. 1,

FIG. 3 is a detailed sectional view in side elevation of the pump,

FIG. 4 is a cross-sectional view taken along the line 4-4 of FIG. 3,

FIG. 5 is a cross-sectional view taken along the line 5-5 of FIG. 3,

FIG. 6 is a view similar to FIG. 1 but showing a mod ification of the invention,

FIG. 7 is a detailed sectional view in side elevation of the FIG. 6 pump,

FIG. 8 is a sectional end view of the FIG. 6 pump,

FIG. 9 is a detailed sectional view in side elevation showing a further modification of the invention,

FIG. 10 is a phantom perspective of the FIG. 9 modification,

FIG. 11 is a cross-sectional view taken along 1111 of FIG. 10,

FIG. 12 is a cross-sectional view taken along 12-12 of FIG. 10,

FIG. 13 is a cross-sectional view taken along 13-13 of FIG. 10,

the line the line the line FIG. 14 is a sectional side view of a further modification of the invention, and,

FIG. 15 is a view in perspective of the FIG. 14 pump, partially cut away to show details of construction.

Referring now to the drawings, the reference character 10 generally indicates an electro-magnetic pump having a tubular cylindrical conduit 12 housing a pair of interleaved spiral bafiles 14 and 16 of electrically insulating material. Each of the bafiles has its outer end attached to the inner wall of the conduit 12 along lines of contact which are angularly spaced from one another. The inner ends of each baffle are connected to an electrically conductive rod 18 extending co-axially through the conduit 12 with the line of contact of one battle with the rod 18 being angularly spaced from the line of contact for the other battle. The batfles being thus spaced from one another define a pair of separate spiral passages between the outer wall of the conduit and the rod 18.

Extending along the wall of the conduit 12 are a pair of strip electrodes 20 and 22 in spaced parallel relation. The electrode 20 lies adjacent the line of contact between baflle 14 and the inner wall of the conduit 12 while the electrode 22 lies adjacent to the line of contact between the spiral baflle 16 and the conduit wall. Thus, each electrode is in separate communication with a spiral passage between the rod 18 and conduit wall. As best shown in FIG. 1, each electrode 20 and 22 has sections alternately exposed, as indicated by the reference character 24, and insulated, as indicated by the reference character 26, with the exposed and insulated sections of the two strip electrodes being staggered with respect to one another whereby, assuming the conduit is filled with an electrically conductive fluid, a DC current applied to the strip electrodes will cause an electric current to flow spirally inwardly to the central conductive rod 18 in one section of the pump, will flow axially along the rod 18 to an axially adjacent section of the pump and then flow spirally outward to an exposed electrode section. It will be understood that only one of the two spiral passages is employed in each section of the pump and it will also be understood that the spiral passage that is not in use in a particular section must be insulated at both the inner and outer ends to prevent leakage currents.

As suggested in FIG. 2 the spiral baflle arrangement results in electric currents flowing in spiral sheets with the flow in one section of the pump being clockwise and in an axially joining section the flow being counterclockwise. Each spiral sheet of current forms a fluid electromagnet each having a polarity in opposition to an adjacent fluid electro-magnet. FIG. 2 while the several spiral sheets are shown axially spaced from one another, this is only for purpose of illustration and in practice the several spiral sheets will be immediately adjacent to one another in end to end relation since the spiral baflles 14 and 16 are continuous throughout the length of the pump.

Wound about the outer cylindrical surface of the conduit 12 are a series of fixed electro-magnets 28, each comprising a winding 30 and an iron jacket 32 for reducing the reluctance of the magnetic circuit. Electro-magnets 28 are disposed coaxially with the conduit 12 and each is oriented with its magnetic field opposing that of an adjacent electro-magnet. In practice this may be done by means of a continuous conductor with the direction of winding 30 of the coil for one electro-magnet being reversed from the adjacent electro-magnet, as suggested in FIG. 1.

Each fluid electro-magnet defined by a spiral bafiie section has substantially the same axial length as the fixed electro-magnet 28 but the fluid electro-magnet and the fixed electro-magnets are arranged so that one overlaps the other by half a length. With this arrangement, each spiral of conducting fluid acts as a fluid electro-magnet having its own flux pattern which is similar to the flux pattern of a fixed eleetro-magnet 28. By reason of the It will be understood that in fact that the direction of the fluid electro-magnets reverse from one section to another, the fields developed by the fluid electro-magnets will oppose one another. In FIG. 2 the polarity of the fields of the fluid elcctro-magnet are shown in relation to the polarity of the fields of the fixed clectro-magnets with the several fields being arranged to produce a component of force axially along the conduit. In FIG. 2 it will be seen that the right hand or north pole of the fluid electro-magnet A is located midway between the poles of a fixed electro-magnet 28. This will produce a magnetic repulsion to the right between the north pole of the fluid electro-magnet A and the north pole of the first fixed electro-magnet 22). At the same time there will be an attraction between he south pole of the fluid electro-magnet A and the north pole of the fixed eleetro-magnet 28. The result will be that the conductive fluid, which is free to flow axially, will be pumped to the right along the conduit l2 as viewed in FIGS. 1 and 2.

This action will be repeated in stages along the length of the pump. For example, as the fluid moves from one baflle section to the adjoining bafile section, the spiral electric current flow will be reversed so that the polarity of the fluid electro-nzagnet B will be opposing that of the electro-magnet A. Thus the north pole of the fluid electro-mngnet B will be attracted to the south pole common to the first two fixed electro-magnets 28 and there will be a repulsion between the south pole of the second fluid electro-magnct B and the south pole common to the first two fixed electro-magnets 28. Since the conductive fluid carries the electric current that establishes the field of the fluid electro-magnet, the conductive fluid is propelled axially along the conduit.

Insofar as the magnetic poles of the fixed electromagnets and the fluid electro-magnets maintain their position relative to one another because of the spiral battles and the electro-magnets 28 are fixed relative to one another only the fluid can move and the propulsive force remains constant.

By employing a double spiral bafile so as to form two spiral passages for the flow of current with alternate passages being used in alternate adjacent pump sections. current leakage is substantially eliminated since the shortest path between an electrode and the axial core is through the spiral passages rather than axially along the con .uit. FIGS. 4 and 5 show current flow for different sections of the pump.

Referring now more particularly to FIGS. 6, 7, and 8 there is illustrated a modification of the invention and in this embodiment, like reference characters correspond to like parts in the principal embodiment. In the FIG. 6 modification, coil windings 34 have been incorporated into the pump and are disposed along the center conducting rod 18 which typically is formed from iron or other suitable core material. The windings 34 arranged in a manner similar to the windings 30 of the fixed electro-magnets 28, that is to say, the electro-magnets defined by the windings are arranged in end-to-end relation with each electro-magnet having a polarity arrangement opposing that of an adjacent electro-magnet. Also, the ends of each electro-magnet formed by the windings 34 are substantially even with the ends of the electro-magnets 28 so that the lines of the magnet flux from the eleetromagnet flux from the electro-magnets 28 are forced to go to the center line of the conduit before passing axially towards the opposite pole. This will have the advantage of maximizing the pressure exerted on the conductive fluid which flows in the annular space between the two sets of concentric fixed coils. Insofar as the polar relationship of the inner and outer electro-magnets correspond with one another, they have the effect of creating a stronger fixed magnetic pole by reducing the flux leakage (flux that short circuits along the conduit rather than serving to strengthen the pole) and by reducing the amount of distortion in the fixed magnetic field resulting from the,

intcraction between the fixed field and the field established by the conductive fluid. This also permits closer spacing of the poles thus producing more pressure for a given amount of pipe friction.

Referring now more particularly to FIG. 9, there illustrated another modification of the invention and, as before, like reference characters, indicate components similar to the principal embodiment. In the P16. 9 pump, the inner windings 34 of the P16. 6 embodiment are replaced by a set of interleaved spiral baflles 36 and 38 mounted between the core rod 18 and a concentric tubular conduit 40 spaced from and extending co-axially within the outer conduit 12. The bafile arrangement 15 similar to that of the spiral baflles 14 and 16 of the prior embodiment with the exception that the direction of the spiral is reversed and the fluid turns in the inner annulus are arranged with their poles in alignment with the fixed electro-magnets 28 and thus in overlapping relation with the poles of the fluid electro-magnets in the outer annulus. In this fashion, the inner fluid electro-magnets w1ll serve the same function as the windings 34 of the FIG. 6 embodiment. That is to say, they will force the lines of magnetic flux from the fixed electro-magnets 28 to go to the center line of the conduit before passing axially toward the opposite pole. It will be understood that the fiuid contained within the inner annulus will be thereby pumped in a direction axially opposite to the fluid pumped in the outer annulus. This configuration is useful in the pumping of molten metals of the like since it eliminates the need for cooling copper turns on the inner core. In this manner, two pumps are placed in parallel instead of only a single pump. The outer portion of the fixed magnetic field may also be modified by employing further conductive fluid turns in another outer annulus in place of the copper windings shown.

FIGS. 10 through 13 show the relationship between the fluid electro-magnets and the fixed electro-magnets of the FIG. 9 embodiment in addition to the unique circuit arrangement and the current flow through various sections of the pump. As best shown in FIG. 10, the outer conduit 12 is provided with the fixed electro-magnets 28 evenly distributed along the conduit with adjacent poles opposing one another. Strip electrodes 20 and 22 are disposed along the conduit walls preferably 180 apart. Each strip electrode 20 and 22 is divided into sectors of equal length which are alternately exposed and insulated from the fluid within the conduit. As shown in FIG. 10, the shaded sectors of the strips indicate an exposed electrode while the unshaded portions indicate exposed sectors and it will be seen that the sectors are staggered with respect to one another so that where one sector is exposed the opposite sector in the other electrode is insulated.

Mounted lengthwise along the outer surface of the inner conduit 40 is an electrode strip section 42 which lies parallel to the strip 20 and on the opposite side of the conduit 40 at the inner end of the spiral passage communicating with the electrode 20. Thus, a current applied to the electrode 20 will pass clockwise through a spiral path to the electrode 42. The circuit to the conductive rod 18 will be completed by the current flowing serially from the electrode 42 to a strip electrode 44 which is in electrical contact with the electrode 42 but is mounted along the inner wall of the conduit 40 in an overlapping relation. It will be understood that the electrode 44 will be of substantially the same length as a fixed electro-magnet 28 and will have its ends substantially aligned therewith. The spiral baffles 33 within the inner conduit 40 are wound in a direction reverse to that of the outer bafiles 14 and 16 whereby a fluid electro-magnet is formed by the current flowing between the electrode 44 and the rod 18. This fluid electro-magnet will have its poles arranged in the same relative position as the fixed electro-magnets 28. From the electro-magnet 44 the current flows spirally into the rod 18 and axially along the rod to an adjacent inner fluid electro-magnet where it will flow outwardly in a clockwise direction through a spiral path to a strip electrode 46 mounted on the inner wall of the conduit 40. As before, the electrode 46 is arranged generally in alignment with its related fixed electro-magnet 28. The current flow is such that a flux pattern is established opposing that of the adjacent inner fiuid electro-magnet. From the electrode 46 the current flows to a strip electrode 48 mounted along the outer surface of the conduit 40 to communicate with the spiral passage which terminates at an exposed sector of the strip electrode 22, the flow being counterclockwise and setting up a field opposing that of the adjacent outer fluid electro-magnet. This is repeated from one section of the pump to the next to form a series of concentric inner and outer fluid electro-magnets in endto-end relation and of opposing polarity.

Referring now more particularly to FIGS. 14 and 15, there is illustrated a further modification and, in this embodiment, means are provided to reduce flux leakage, armature reaction and fringing, all of which attenuate the electro-magnetic poles and reduce the eificiency of the device.

As illustrated, the pump of FIGS. 14 and 15 includes a conduit 50, a pair of spaced, interleaved spiral baflles 52 and 54 and an axial core 56. Both the core and the conduit are formed with annular shoulders or pole pieces 58 and 60 facing oppositely one another and spaced evenly along the length of the pump. Between each pair of shoulders are windings 62 and 64 forming fixed inner and outer concentric electro-magnets having the same function as the electro-magnets of the FIG. 6 embodiment. Since the effective air gap between the conduit wall and the axial core is relatively large, it is desirable to enhance the strength of the poles. To this end conductive strips 66 and 68 are imbedded in the spiral bafiles 52 and 54 on either side of the pole pieces for the fixed magnetic fields. Each conductive strip 66 and 68 has an electric current flowing in the same direction as that of the outer fixed coil with the result that on either side of a pole face, there is a conductive spiral, each having a current flow in opposite directions. The strips are insulated from the conductive fluid and from each other and combine to concentrate the magnetic flux between the inner and outer fixed electro-magnets and thereby strengthen their magnetic poles.

The magnetic circuit may be further improved by imbedding a ferro-magnetic strip 65 in the spiral between the two conductive strips 66 and 68 between axially adjacent fixed electro-magnets. The flux would saturate the strip in the direction of the spiral but would provide a lower reluctance path perpendicular to the spiral surface so as to augment further the magnetic pole strength. The ferro-magnetic strip would also be insulated from the conductive strips and from the conductive fluid. As shown in FIG. 14, the imbedded strips do not interfere with the smooth surfaces of the bafiles thus avoiding disturbances of the fluid flow.

While the invention has been described with particular reference to the illustrated embodiments, it will be understood that numerous modifications ther,eto will appear to those skilled in the art. Also, it will be understood that the above description and accompanying drawings should be taken as illustrative of the invention and not in a limiting sense.

Having thus described the invention, what I claim and desire to obtain by Letters Patent of the United States is:

1. A device for pumping an electrically conductive fluid medium, comprising a conduit for said medium, a plurality of fixed electro-magnets mounted in end-to-end relation along said conduit with adjacent electro-magnets arranged in polar opposition, first and second electrodes extending in spaced parallel relation lengthwise adjacent the inner surface of said conduit, a conductor parallel to said electrodes and disposed inwardly thereof, a pair of electrically insulating baflles spaced from one another and extending in separate spiral paths between said conductor and the inner wall of said conduit to define two separate spiral passages, the outer end of one baflle being attached to said wall along a line adjacent one of said electrodes and the outer end of the other bafi le being attached to said wall along a line adjacent the other of said electrodes, said electrodes having sectors extending in overlapping relation to said fixed electro-magnets whereby a D.C. current applied to such electrodes will produce an inward spiral current through one passage in one portion of said conduit and an outward spiral current through the other passage in an axially adjacent portion of said conduit and forming thereby fluid electro-magnets of opposing polar relation which coact with said fixed electromagnets to pump said medium axially along said conduit.

2. A device according to claim 1 including a jacket of permeable metal about said electro-magnets for reducing the reluctance of the magnetic circuit.

3. A device for pumping an electrically conductive fluid medium, comprising a conduit for said medium, a plurality of fixed electro-magnets mounted in end-to-end relation along said conduit with adjacent electro-magnets arranged in polar opposition, first and second electrodes extending in spaced parallel relation lengthwise adjacent the inner surface of said conduit, a conductor parallel to said electrodes and disposed inwardly thereof, a pair of electrically insulating baffles spaced from one another and extending in separate spiral paths between said conductor and the inner wall of said conduit to define two separate spiral passages each communicating with one of said electrodes, said electrodes having sectors that are alternately exposed and insulated in staggered relation, said sectors extending in overlapping relation to said fixed electro-magnets whereby a D.C. current applied to said electrodes will produce an inward spiral current through one passage in one portion of said conduit and an outward spiral current through the other passage in an axially adjacent portion of said conduit and forming thereby fluid electromagnets of opposing polar relation which co-act with said fixed electro-magnets to pump said medium axially along said conduit.

4. A device according to claim 3 including a plurality of fixed inner electro-magnets disposed in end-to-end relation along said conductor, said inner electro-magnets being co-extensive with and of the same polarity as said firstmentioned fixed electro-magnets for concentrating the fiux of said first-mentioned electro-magnets to the center line of said conduit.

5. A device for pumping an electrically conductive fluid medium, comprising a conduit for said medium, a plurality of fixed electro-magnets mounted in end-to-end relation along said conduit with adjacent electro-magnets arranged in polar opposition, first and second electrodes extending in spaced relation lengthwise of said conduit, a conductor disposed inwardly of said electrodes, a pair of electrically insulating bafiles spaced from one another and extending in separate spiral paths between said conductor and the inner wall of said conduit to define two separate spiral passages each communicating with one of said electrodes, said electrodes having sectors that are alternately exposed and insulated in staggered relation, said sectors extending in overlapping relation to said fixed electro-magnets whereby a D.C. current applied to said electrodes will produce an inward spiral current through one passage in one portion of said conduit and an outward spiral current through the other passage in an axially adjacent portion of said conduit and forming thereby fluid electro-magnets of opposing polar relation which co-act with said fixed electro-magnets to pump said medium axially along said conduit.

6. A device according to claim 5 including electromagnetic means disposed along the center of said conduit for concentrating the flux of said fixed electro-magnets towards the center of said conduit.

7. A device for pumping an electrically conductive fluid medium, comprising a conduit for said medium,

a plurality of outer electro-magnets mounted in end-toend relation along said conduit with adjacent electromagnets arranged in polar opposition, electrodes disposed in spaced relation on said conduit, a conductor disposed inwardly of said electrodes, a pair of electrically insulating baflies spaced from one another and extending in separate spiral paths between said conductor and the inner wall of said conduit to define two separate spiral passages each communicating with one of said electrodes, said electrodes having sectors that are alternately exposed and insulated in staggered relation, said sectors extending in overlapping relation to said fixed electro-magnets whereby a D.C. current applied to said electrodes will produce an inward spiral current through one passage in one portion of said conduit and an outward spiral current through the other passage in an axially adjacent portion of said conduit and forming thereby fluid electromagnets of opposing polar relation which co-act with said fixed electro-magnets to pump said medium axially along said conduit, and a plurality of inner electro-magnets disposed along said conductor in register with and having the same polarity as said outer electro-magnets.

8. A device according to claim 7 including spiral windings between matching poles of said inner and outer electro-magnets for concentrating the flux between said poles.

9. A device for pumping an electrically conductive fluid medium, comprising a conduit for said medium, a plurality of outer clectro-magnets mounted in cnd-to-cnd relation along said conduit with adjacent electro-magnets arranged in polar opposition, a conductor disposed inwardly of said conduit walls, a pair of electrically insulating bafiles spaced from one another and extending in separate spiral paths between said conductor and the inner wall of said conduit to define two separate spiral passages, means for applying a D.C. current inwardly through one spiral passage in one portion of said conduit and outwardly through the other passage in an axially adjacent portion of said conduit and forming thereby fluid electro-magnets of opposing polar relation which coact with said outer electro-magnets to pump said medium axially along said conduit.

10. A device according to claim 9 including a plurality of inner electro-magnets disposed in end-to-end relation along said conductor for concentrating the flux of said outer elcctro-magnets towards the center of said conduit.

11. A device according to claim 10 wherein inner electro-magnets comprise electrical windings.

12. A device according to claim 10 wherein said inner electro-magnets comprise spiral baflles defining spiral fluid passages whereby second fluid electro-magnets may be developed by the application of a D.C. current between the ends of said passages.

13. A device according to claim 9 wherein said outer electro-magnets comprise spiral balfles defining spiral fluid passages whereby outer fluid electro-magnets may be developed by the application of a D.C. current between the ends of said passages.

14. A device according to claim 10 including insulated spiral conducting means extending between matching pole ends of said inner and outer electro-magnets for concen trating the flux of said outer electro-magnets to the center of said conduit.

15. A device according to claim 14 including insulated spiral ferro-magnetic means adjacent said conducting means for reducing the reluctance of the flux circuit between said matching poles.

16. A device for pumping an electrically conductive fluid medium, comprising a conduit for said medium, a plurality of outer electro-magnets mounted in end-to-end relation along said conduit with adjacent electro-rnagnels arranged in polar opposition, a conductor disposed inwardly of said conduit walls, a pair of electrically insulated bafiles spaced from one another and extending in separate spiral paths between said conductor and the 9 inner wall of said conduit to define two separate spiral passages, means for applying a DC current inwardly through one spiral passage in one portion of said conduit and outwardly through the other passage in an axially adjacent portion of said conduit and forming thereby fluid electro-magnets of opposing polar relation which co-act with said outer electro-magnets to pump said medium axially along said conduit, a plurality of inner electromagnets disposed in end-to-end relation along said conductor and arranged in polar opposition corresponding to said outer electro-magnets and spiral conducting means in series with each pair of inner and outer electro-magnets and coextensive therewith. said conducting means being insulated from said medium.

References Cited by the Examiner UNITED STATES PATENTS 1,608,560 11/1926 Jones 336-181 2,905,915 9/1959 Harris 336--181 2,982,214 5/1961 Cochran 103l LAURENCE V. EFNER, Primary Examiner. 

1. A DEVICE FOR PUMPING AN ELECTRICALLY CONDUCTIVE FLUID MEDIUM, COMPRISING A CONDUIT FOR SAID MEDIUM, A PLURALITY OF FIXED ELECTRO-MAGNETS MOUNTED IN END-TO-END RELATION ALONG SAID CONDUIT WITH ADJACENT ELECTRO-MAGNETS ARRANGED IN POLAR OPPOSITION, FIRST AND SECOND ELECTRODES EXTENDING IN SPACED PARALLEL RELATION LENGTHWISE ADJACENT THE INNER SURFACE OF SAID CONDUIT, A CONDUCTOR PARALLEL TO SAID ELECTRODES AND DISPOSED INWARDLY THEREOF, A PAIR OF ELECTRICALLY INSULATING BAFFLES SPACED FROM ONE ANOTHER AND EXTENDING IN SEPARATE SPIRAL PATHS BETWEEN SAID CONDUCTOR AND THE INNER WALL OF SAID CONDUIT TO DEFINE TWO SEPARATE SPIRAL PASSAGES, THE OUTER END OF ONE BAFFLE BEING ATTACHED TO SAID WALL ALONG A LINE ADJACENT ONE OF SAID ELECTRODES AND THE OUTER END OF THE OTHER BAFFLE BEING ATTACHED TO SAID WALL ALONG A LINE ADJACENT THE OTHER OF SAID ELECTRODES, SAID ELECTRODES HAVING SECTORS EXTENDING IN OVERLAPPING RELATION TO SAID FIXED ELECTRO-MAGNETS WHEREBY A D.C. CURRENT APPLIED TO SUCH ELECTRODES WILL PRODUCE AN INWARD SPIRAL CURRENT THROUGH ONE PASSAGE IN ONE PORTION OF SAID CONDUIT AND AN OUTWARD SPIRAL CURRENT THROUGH THE OTHER PASSAGE IN AN AXIALLY ADJACENT PORTION OF SAID CONDUIT AND FORMING THEREBY FLUID ELECTRO-MAGNETS OF OPPOSING POLAR RELATION WHICH COACT WITH SAID FIXED ELECTROMAGNETS TO PUMP SAID MEDIUM AXIALLY ALONG SAID CONDUIT. 